bims-mosdis 2023-07-09 papers

bims-mosdis

Biomed News

on Mosquito distribution and disease

Issue of 2023–07–09
ten papers selected by
Richard Halfpenny, Staffordshire University

First report of Anopheles stephensi in Southern Ethiopia.
Spatial distribution and temporal dynamics of invasive and native mosquitoes in a large Mediterranean city.
Identification of risk factors and mosquito vectors associated with dengue virus infection in American Samoa, 2017.
Interactive effects of climate, land use and soil type on Culex pipiens/torrentium abundance.
Population genetics of an invasive mosquito vector, Aedes albopictus in the Northeastern USA.
Malaria vector sibling species distribution in different endemic districts of Punjab, India.
Phylogeny and spatial distribution of Japanese encephalitis virus vector species in Cambodia.
Dengue in Bangladesh.
First US Malaria Cases in 20 Years Prompt CDC Advisory.
Malaria among members of the U.S. Armed Forces, 2013-2022.

Res Sq. 2023 Jun 15. pii: rs.3.rs-3052835. [Epub ahead of print]

First report of Anopheles stephensi in Southern Ethiopia.

Dawit Hawaria, Solomon Kibret, Daibin Zhong, Ming-Chieh Lee, Kidane Lelisa, Belayneh Bekele, Muntasha Birhanu, Mathe Mengesha, Hiwot Solomon, Delenesaw Yewhalaw, Guiyun Yan.

Background Anopheles stephensi is an emerging exotic invasive urban vector of malaria in East Africa. The World Health Organization recently announced an initiative to take concerted actions to limit this vector's expansion by strengthening surveillance and control in invaded and potentially receptive territories in Africa. This study sought to determine the geographic distribution of An. stephensi in southern Ethiopia. Methods A targeted entomological survey, both larvae and adult, was conducted in Hawassa city, Southern Ethiopia between November 2022 and February 2023. Anopheles Larvae were reared to adults for species identification. CDC light traps and BG Pro traps were used overnight both indoor and outdoor at selected houses to collect adult mosquitoes in the study area. Prokopack Aspirator was employed to sample indoor resting mosquitoes in the morning. Adults of An. stephensi was identified using morphological keys, and then confirmed by PCR. Results Larvae of An. stephensi were found in 28 (16.6%) of the 169 potential mosquito breeding sites surveyed. Out of 548 adult female Anopheles mosquitoes reared from larvae, 234 (42.7%) were identified to be An. stephensi morphologically. A total of 449 female anophelines were caught, of which 53 (12.0%) were An. stephensi . Other anopheline species collected in the study area included An. gambiae (s.l.), An. pharoensis, An. coustani , and An. demeilloni. Conclusion The study, for the first time, confirmed the presence of An. stephensi in southern Ethiopia. The presence of both larval and adult stages of this mosquito attest that this species established a sympatric colonization with native vector species such as An. gambiae (s.l.) in Southern Ethiopia. The findings warrant further investigation on the ecology, behavior, population genetics, and role of An. stephensi in malaria transmission in Ethiopia.

DOI: https://doi.org/10.21203/rs.3.rs-3052835/v1
Sci Total Environ. 2023 Jul 04. pii: S0048-9697(23)03945-1. [Epub ahead of print] 165322

Spatial distribution and temporal dynamics of invasive and native mosquitoes in a large Mediterranean city.

M Ferraguti, J Martínez-de la Puente, S Brugueras, J P Millet, C Rius, A Valsecchi, J Figuerola, T Montalvo.

  Mosquitoes, including invasive species like the Asian tiger mosquito Aedes albopictus, alongside native species Culex pipiens s.l., pose a significant nuisance to humans and serve as vectors for mosquito-borne diseases in urban areas. Understanding the impact of water infrastructure characteristics, climatic conditions, and management strategies on mosquito occurrence and effectiveness of control measures to assess their implications on mosquito occurrence is crucial for effective vector control. In this study, we examined data collected during the local vector control program in Barcelona, Spain, focusing on 234,225 visits to 31,334 different sewers, as well as 1817 visits to 152 fountains between 2015 and 2019. We investigated both the colonization and recolonization processes of mosquito larvae within these water infrastructures. Our findings revealed higher larval presence in sandbox-sewers compared to siphonic or direct sewers, and the presence of vegetation and the use of naturalized water positively influenced larval occurrence in fountains. The application of larvicidal treatment significantly reduced larvae presence; however, recolonization rates were negatively affected by the time elapsed since treatment. Climatic conditions played a critical role in the colonization and recolonization of sewers and urban fountains, with mosquito occurrence exhibiting non-linear patterns and, generally, increasing at intermediate temperatures and accumulated rainfall levels. This study emphasizes the importance of considering sewers and fountains characteristics and climatic conditions when implementing vector control programs to optimize resources and effectively reduce mosquito populations.

Keywords:  Aedes albopictus; Bacillus thuringiensis israelensis; Culex pipiens; Culicidae; Larvae control; Monitoring and surveillance; Mosquito-borne diseases; Vector control

DOI:  https://doi.org/10.1016/j.scitotenv.2023.165322
PLOS Glob Public Health. 2023 ;3(7): e0001604

Identification of risk factors and mosquito vectors associated with dengue virus infection in American Samoa, 2017.

Tyler M Sharp, A John Tufa, Caitlin J Cotter, Matthew J Lozier, Gilberto A Santiago, Stephanie S Johnson, Mary Mataia'a, Stephen H Waterman, Jorge L Muñoz-Jordán, Gabriela Paz-Bailey, Ryan R Hemme, Mark A Schmaedick, Scott Anesi.

INTRODUCTION: The first outbreak of dengue in American Samoa was reported in 1911. Sporadic outbreaks have been reported since, as were outbreaks of other pathogens transmitted by Aedes species mosquitoes including Ross River, chikungunya, and Zika viruses. During an outbreak of dengue virus-type 2 (DENV-2) in 2016-2018, we conducted household-based cluster investigations to identify population-specific risk factors associated with infection and performed entomologic surveillance to determine the relative abundance of Ae. aegypti and Ae. polynesiensis.
METHODS AND FINDINGS: We contacted dengue patients who had tested positive for DENV infection and offered them as well as their household members participation in household-based cluster investigations. For those that accepted participation, we also offered participation to residents of households within a 50-meter radius of each case-patient's home. Questionnaires were administered and serum specimens collected for testing by RT-PCR and anti-DENV IgM ELISA. Adult female mosquitoes were aspirated from inside and outside participating households and tested by RT-PCR. We analyzed characteristics associated with DENV infection in bivariate analyses. A total of 226 participants was enrolled from 91 households in 20 clusters. Median age of participants was 34 years (range: <1-94), and 56.2% were female. In total, 7 (3.2%) participants had evidence of DENV infection by IgM ELISA (n = 5) or RT-PCR (n = 2). Factors significantly associated with DENV infection were reporting a febrile illness in the past three months (prevalence ratio: 7.5 [95% confidence interval: 1.9-29.8]) and having a household septic tank (Fisher's Exact Test, p = 0.004). Of 93 Ae. aegypti and 90 Ae. polynesiensis females collected, 90% of Ae. aegypti were collected inside homes whereas 83% of Ae. polynesiensis were collected outside homes. DENV nucleic acid was not detected in any mosquito pools. Sequencing of the DENV-2 from patient specimens identified the Cosmopolitan genotype of DENV-2 and was most closely related to virus detected in the Solomon Islands during 2016.
CONCLUSIONS: This investigation demonstrated that dengue is a continuing risk in American Samoa. Increased frequency of infection among residents with a septic tank suggests a need to investigate whether septic tanks serve as larval habitats for mosquito vectors of DENV in American Samoa. Future efforts should also evaluate the role of Ae. polynesiensis in DENV transmission in the wild.

DOI: https://doi.org/10.1371/journal.pgph.0001604
One Health. 2023 Dec;17 100589

Interactive effects of climate, land use and soil type on Culex pipiens/torrentium abundance.

Louie Krol, Rody Blom, Martha Dellar, Jordy G van der Beek, Arjan C J Stroo, Peter M van Bodegom, Gertjan W Geerling, Constantianus J M Koenraadt, Maarten Schrama.

  The incidence and risk of mosquito-borne disease outbreaks in Northwestern Europe has increased over the last few decades. Understanding the underlying environmental drivers of mosquito population dynamics helps to adequately assess mosquito-borne disease risk. While previous studies have focussed primarily on the effects of climatic conditions (i.e., temperature and precipitation) and/or local environmental conditions individually, it remains unclear how climatic conditions interact with local environmental factors such as land use and soil type, and how these subsequently affect mosquito abundance. Here, we set out to study the interactive effects of land use, soil type and climatic conditions on the abundance of Culex pipiens/torrentium, highly abundant vectors of West Nile virus and Usutu virus. Mosquitoes were sampled at 14 sites throughout the Netherlands. At each site, weekly mosquito collections were carried out between early July and mid-October 2020 and 2021. To assess the effect of the aforementioned environmental factors, we performed a series of generalized linear mixed models and non-parametric statistical tests. Our results show that mosquito abundance and species richness consistently differ among land use- and soil types, with peri-urban areas with peat/clay soils having the highest Cx. pipiens/torrentium abundance and sandy rural areas having the lowest. Furthermore, we observed differences in precipitation-mediated effects on Cx. pipiens/torrentium abundance between (peri-)urban and other land uses and soil types. In contrast, effects of temperature on Cx. pipiens/torrentium abundance remain similar between different land use and soil types. Our study highlights the importance of both land use and soil type in conjunction with climatic conditions for understanding mosquito abundances. Particularly in relation to rainfall events, land use and soil type has a marked effect on mosquito abundance. These findings underscore the importance of local environmental parameters for studies focusing on predicting or mitigating disease risk.

Keywords:  Mosquito surveillance; Mosquito-borne diseases; One health; Usutu virus; Water management; West Nile virus

DOI:  https://doi.org/10.1016/j.onehlt.2023.100589
NeoBiota. 2022 ;78 99-127

Population genetics of an invasive mosquito vector, Aedes albopictus in the Northeastern USA.

Andrea Gloria-Soria, Talya Shragai, Alexander T Ciota, Todd B Duval, Barry W Alto, Ademir J Martins, Kathleen M Westby, Kim A Medley, Isik Unlu, Scott R Campbell, Malgorzata Kawalkowski, Yoshio Tsuda, Yukiko Higa, Nicholas Indelicato, Paul T Leisnham, Adalgisa Caccone, Philip M Armstrong.

  The Asian tiger mosquito (Aedes albopictus) arrived in the USA in the 1980's and rapidly spread throughout eastern USA within a decade. The predicted northern edge of its overwintering distribution on the East Coast of the USA roughly falls across New York, Connecticut, and Massachusetts, where the species has been recorded as early as 2000. It is unclear whether Ae. albopictus populations have become established and survive the cold winters in these areas or are recolonized every year. We genotyped and analyzed populations of Ae. albopictus from the northeast USA using 15 microsatellite markers and compared them with other populations across the country and to representatives of the major global genetic clades to investigate their connectivity and stability. Founder effects or bottlenecks were rare at the northern range of the Ae. albopictus distribution in the northeastern USA, with populations displaying high levels of genetic diversity and connectivity along the East Coast. There is no evidence of population turnover in Connecticut during the course of three consecutive years, with consistent genetic structure throughout this period. Overall, these results support the presence of established populations of Ae. albopictus in New York, Connecticut, and Massachusetts, successfully overwintering and migrating in large numbers. Given the stability and interconnectedness of these populations, Ae. albopictus has the potential to continue to proliferate and expand its range northward under mean warming conditions of climate change. Efforts to control Ae. albopictus in these areas should thus focus on vector suppression rather than eradication strategies, as local populations have become firmly established and are expected to reemerge every summer.

Keywords:  Asian tiger mosquito; colonization; container-breeder; invasion genetics; propagule pressure; range expansion

DOI:  https://doi.org/10.3897/neobiota.78.84986
J Vector Borne Dis. 2023 Apr-Jun;60(2):60(2): 154-160

Malaria vector sibling species distribution in different endemic districts of Punjab, India.

Jaspreet Kaur, Taruna Kaura, Ayush Sharma, Ashish Dhiman, Mangesh K Pangotra, Ashok K Upadhyay, Gagandeep Singh Grover, Surya K Sharma.

   BACKGROUND & OBJECTIVES: Malaria transmission in Punjab, India is mainly seasonal with variation in its endemicity that may be due to varying vector behaviour in different areas of the state, primarily attributed to the existence of sibling species complexes among the vector species. So far there is no report regarding the existence of malaria vectors sibling species in the state of Punjab, therefore, the present study was planned to investigate the status of sibling species of two main vectors of malaria viz. Anopheles culcifacies and Anopheles fluviatilis in different districts of Punjab.
METHODS: Mosquito collections were made through hand catch in the morning hours. Malaria vector species An. culicifacies and An. fluviatilis were morphologically identified and man hour density was calculated. Both the vector species were subjected to molecular assays for sibling species identification through amplification of D3 domain of 28S ribosomal DNA by allele-specific PCR.
RESULTS: Four sibling species of An. culicifacies, were identified viz. A, B, C and E. Species A was identified from Bhatinda district, species B, C and E from. S.A.S. Nagar and species C from Hoshiarpur. Two sibling species S and T of An. fluviatilis were identified from districts S.A.S. Nagar and Rupnagar.
INTERPRETATION & CONCLUSION: Presence of four sibling species of An. culicifacies and two sibling species of An. fluviatilis in Punjab necessitates planning of longitudinal studies to ascertain their role in disease transmission so that appropriate interventions may be applied to achieve malaria elimination.

Keywords:  India; sibling species; malaria vectors; Punjab

DOI:  https://doi.org/10.4103/0972-9062.361170
Med Vet Entomol. 2023 Jul 05.

Phylogeny and spatial distribution of Japanese encephalitis virus vector species in Cambodia.

Rutaiwan Dusadeepong, Pierre-Olivier Maquart, Mallorie Hide, Sebastien Boyer.

  In Southeast Asia, despite the use of Japanese encephalitis vaccines and vaccination coverage, Japanese encephalitis (JE) transmission is still a major public health issue. The main vectors of this virus are mosquitoes from the genus Culex, which diversity and density are important in Southeast Asia. The main vector species of Japanese encephalitis virus (JEV) in Cambodia belong to the Vishnui subgroup. However, their morphological identification solely based on the adult stage remains challenging, making their segregation and detection difficult. In order to identify and describe the distribution of the three main JEV vector species in Cambodia, namely Culex vishnui, Cx. pseudovishnui and Cx. tritaeniorhynchus, mosquito samplings were carried out throughout the country in different environments. Phylogenetic analysis of the cytochrome c oxidase subunit I (coI) gene using maximum-likelihood tree with ultrafast bootstrap and phylogeographic analysis were performed. The three main Culex species are phylogenetically separated, and represent two distinct clades, one with Cx. tritaeniorhynchus and the second with Cx. vishnui and Cx. pseudovishnui, the latter appearing as a subgroup of Cx. vishnui. The phylogeographic analysis shows a distribution of the Vishnui subgroup on the entire Cambodian territory with an overlapped distribution areas leading to a sympatric distribution of these species. The three JEV vector species are geographically well-defined with a strong presence of Cx. pseudovishnui in the forest. Combined with the presence of Cx. tritaeniorhynchus and Cx. vishnui in rural, peri-urban, and urban areas, the presence of JEV-competent vectors is widespread in Cambodia.

Keywords:  Culex; Japanese encephalitis virus; mosquito; phylogeny; phylogeography

DOI:  https://doi.org/10.1111/mve.12678
Int J Infect Dis. 2023 Jun 29. pii: S1201-9712(23)00644-6. [Epub ahead of print]

Dengue in Bangladesh.

Atia Sharmin Bonna, Shahed Rafi Pavel, Tajnuva Mehjabin, Mohammad Ali.

  Dengue is one of the prominent public health concerns in tropical and subtropical regions globally. The dengue epidemic was first observed in the 1780s, mainly in Asia, Africa, and America; however, this virus was found in Bangladesh in 1964. Rapid and unplanned urbanization, global warming, and prolonged rainy season promoted dengue outbreaks in recent years in Bangladesh. Additionally, household hazards contribute to producing an increased number of Aedes mosquitoes. The presence of four subtypes of dengue viruses (DENV) intensified the dengue outbreak and fatalities, especially since the reemergence of dengue DENV 4 caused more death in 2022. Dhaka city and Rohingya refugee camps witnessed the highest prevalence of dengue patients and fatalities. Furthermore, the cocreation of the dengue outbreak and COVID-19 pandemic-related hazards overwhelmed the health system in Bangladesh. The measures previously taken by the Bangladesh government and City Corporation authorities proved inadequate to face the surge of dengue patients during the pandemic. The government of Bangladesh should stress the proper management of a high volume of dengue patients and raise public concern to fight mosquito proliferation in hot spots such as Dhaka city and Rohingya refugee camps.

Keywords:  Aedes; Bangladesh; dengue; global warming; public health; vector

DOI:  https://doi.org/10.1016/j.ijid.2023.06.020
JAMA. 2023 Jul 05.

First US Malaria Cases in 20 Years Prompt CDC Advisory.

Emily Harris.

DOI: https://doi.org/10.1001/jama.2023.12052
MSMR. 2023 03 20. 30(3): 10-15

Malaria among members of the U.S. Armed Forces, 2013-2022.

Armed Forces Health Surveillance Division

Malaria infection remains a potential health threat to U.S. service members located in or near endemic areas due to duty assignment, participation in contingency operations, or personal travel. In 2022, a total of 30 active and reserve component service members were diagnosed with or reported to have malaria, a 42.9% increase from the 21 cases identified in 2021. Over half of the malaria cases in 2022 were caused by Plasmodium falciparum (53.3%; n=16) and one-sixth (16.7%; n=5) were attributed to P vivax. The remaining 9 cases were associated with other or unspecified types of malaria. Malaria cases were diagnosed or reported from 19 different medical facilities-15 in the U.S. and 1 each from Germany, Africa, South Korea, and Japan. Of the 28 cases with a known location of diagnosis, 9 (32.1%) were reported from or diagnosed outside the U.S.